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Energy from turbine - driven generator |
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.*** g80 5/22 p. 29 Watching the World *** Sun Power from Ponds ♦ Israel recently began operating a new electrical generating system based on a shallow pool of water. Located at a small community near the south shore of the Dead Sea, the pond develops high temperatures at its bottom as the sun’s rays penetrate the water. Instead of the hot water rising, as it would normally, salt dissolved near the bottom forms a heavy layer that resists convection. Lighter, fresh surface waters insulate the hot, salty water below, which reaches temperatures as high as 80 degrees C (176° F) at this location. The hot water heats a liquid that boils at low temperature to power a turbine-driven generator. The pilot project produces 150 kilowatts of power day and night from a pool only 7,000 square m (1.7 acres) in area and 2.5 m (8 feet) deep. The system is said to be economical and environmentally harmless.
*** g80 8/8 pp. 12-14 Alcohol for Fuel—The Answer? *** Alcohol for Fuel—The Answer? A report on Brazil’s answer to the energy crisis IN 1979, gas stations in a number of Brazilian cities began to sell alcohol, instead of only gasoline or diesel fuel. The idea is not new. Alexander Graham Bell declared in 1922: “World oil consumption is so great that supplies can only last for a few more generations. The solution is alcohol, a clean and perfect fuel.” To be a real solution, the alcohol must come from a renewable source. The only one available is biomass. What is that? Living, biological matter that can be transformed into energy. The key is photosynthesis. Plants store solar energy in the form of chemical compounds that man can use to produce alcohol—biomass alcohol. Alcohol-powered cars have more than half a century of history in Brazil. In 1919 the governor of Pernambuco State decided to use alcohol for the fleet of government vehicles, and in the 1920’s this state already used alcohol mixtures, with some cars running entirely on this fuel. By 1933, President Getulio Vargas decided to make Rio de Janeiro “the first alcohol-run city in Brazil.” But the effort to convert the city’s 20,000 cars to run on a mixture of 60 percent alcohol had to be abandoned when the alcohol ran out. Other attempts to blend alcohol and gasoline were made in 1938 and 1942, but it was impossible to price alcohol competitively. However, in 1973 the picture began to change. Skyrocketing oil prices and increased consumption had driven the price tag on Brazil’s oil imports from $400 million (U.S.) in 1972 to $4,000 million in 1975. Since Brazil has an abundance of moving water that can be harnessed to generate electricity, the increased cost of oil did not create an energy crisis but, rather, a fuel crisis. The country’s best option for fuel was biomass alcohol. Therefore, in November of 1975 the National Alcohol Program, Proálcool, was started. It covers everything—planting millions of hectares of additional sugarcane, experimenting with other plants, also arranging for storage and marketing. The first stage of the plan was to use up to 20 percent of alcohol mixed with gasoline, since this would not require any adjustments in car engines. After more than three years, up to 16 percent of alcohol is already being added. The Brazilian Alcohol Program has already gone far beyond dreaming. Alcohol production was 740 million L in 1974-75; in 1977-78 it went up to 1,500 million. Plans call for the production of 10,700 million L of alcohol in 1985, which will represent about 5 percent of the energy consumed in the country. Brazil has a total land area of 8.5 million km2 so there is enough land—and sunlight—for the cultivation of plants to produce the necessary raw material. Brazil’s cerrado, its hinterland, of about 2 million km2 is ideal. The primary goal of Proálcool is to produce ethyl alcohol from sugarcane by fermentation and subsequent distillation. Present production is about 3,500 L of alcohol per year for each hectare, but experiments are under way to increase this production. The construction and installation of a plant to produce about 120,000 L of alcohol per day costs about the same as drilling a petroleum well ($10 million, U.S.), but with the guarantee of production. Total installation of such an alcohol distillery takes about three years, whereas an oil field may require five years before it can be used commercially.
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